Donor specific anti-HLA antibodies in hematopoietic stem cell transplantation. Single Center prospective evaluation and desensitization strategies employed.

BACKGROUND: In the setting of mismatched-hematopoietic stem cells transplantation, the detection of antibodies directed against donor-specific HLA allele(s) or antigen(s) (DSA) represents a barrier for engraftment. It is thus necessary to plan an immunosuppressive strategy, or to select an alternative donor. This prospective study aimed at evaluating the efficacy of our strategy for testing DSAs and the efficacy of the desensitization strategy (DS) employed between November 2017 and November 2020. MATERIALS AND METHODS: The anti-HLA antibody search was performed using the Luminex bead assays (Lifecode ID and LSA I/II-Immucor) and expressed as mean fluorescence intensity (MFI >1,000 positive). If the patient had DSAs and no alternative donors, a DS was employed with rituximab (day -15), 2 single volume plasmaphereses (PP; days -9 and -8), intravenous immunoglobulins (day -7) and infusion of HLA selected platelets, if persistent DSAs were directed against class I HLA. DS was scheduled with or without PP, according to the DSA MFI (>1,000 or <5,000) and FCXM (flow cytometry crossmatch). RESULTS: Twenty-two out of 126 patients (17.46%) showed anti-HLA antibodies, 5 of them DSAs (3.97% of total); 3 patients underwent DS obtaining engraftment. Female gender (p=0.033) and a history of previous pregnancies or miscarriages (p=0.009) showed a statistically significant impact on alloimmunization. Factors associated with a delayed neutrophil engraftment were patient's female gender (p=0.039), stem cell source (p=0.025), and a high HSCT-specific comorbidity index (p=0.028). None of the analyzed variables, including the DSA detection, influenced engraftment. CONCLUSIONS: Our study confirms the importance to test DSAs in mismatched-hematopoietic stem cells transplantation The DS used proved successful in removing DSAs. Prospective multicenter studies are needed to better define and validate consensus strategies on DSA management in HSCT.

A survey on preoperative autologous blood donation policy in bone marrow stem cell donors in Italy.

BACKGROUND: The high safety of homologous blood components, together with the introduction of the Patient Blood Management strategy, has led to the progressive abandonment of preoperative autologous blood donation (PAD) in surgery. Furthermore, recent scientific publications provide evidence about the non-usefulness of PAD in the collection of hematopoietic stem cells (HSC) from bone marrow (BM), also in consideration of harvest procedure safety. Nevertheless, no conclusive studies have been published yet. MATERIALS AND METHODS: Blood Establishments (BE) and Bone Marrow Collection Centers (BMCC) participated in a specific qualitative survey proposed by Italian National Blood and Transplant centers with the support of the relevant Italian Scientific Societies. The survey aimed at evaluating the policy adopted for PAD in related and unrelated adult HSC donors in Italy during the period 2018-2020. RESULTS: Forty-one BE corresponding to 37 BMCC filled in the questionnaire. Of 830 BM donors, 661 (80%) underwent 1063 PAD (mean 1.6 PAD/donor). The remaining 169 donors (20%) underwent BM harvest without PAD. No serious adverse events were reported for either donor group. In the case of ineligibility of donors for the PAD program, due to low hemoglobin values, 7/10 centers shifted donors to peripheral blood stem cell collection and three centers chose a different donor. Remarkably, only 51% of the PAD units requested were eventually transfused during the BM harvest process. Finally, the iron support policy among centers was heterogeneous. DISCUSSION: The results of this survey show that PAD is heterogeneously applied in Italian BMCC, as in other countries. However, all BMCC except two are willing to adopt a Patient Blood Management strategy as an alternative approach to adult related and unrelated BM donor harvests.

Immuno-hematological monitoring after allogeneic stem cell transplantation: a single-center, prospective study of 104 patients.

BACKGROUND: The impact of ABO incompatibility on the outcome of hematopoietic stem cell transplantation (HSCT) is still debated. We report the results of a prospective, single-center study evaluating the impact of ABO mismatch on the development of immediate and late immuno-hematological complications, and the efficacy of the protocol used at the "Sapienza" University (Rome, Italy) to manage ABO incompatibility in patients undergoing HSCT. MATERIALS AND METHODS: From January 2013 to December 2016, we prospectively analyzed all patients undergoing HSCT. Graft manipulation or desensitization strategies were used according to ABO incompatibility, donor sex and donor transfusion history. Red blood cell and platelet transfusions were given based on immunohematological features. RESULTS: From January 2013 to December 2016, 104 consecutive patients underwent HSCT from a matched related donor (29.81%), matched unrelated donor (53.58%), cord blood (1.9%) or haploidentical donor (14.42%). Forty-nine patients (47%) were ABO-identical and 55 (53%) ABO-incompatible (23 major, 25 minor, 7 bidirectional). Donor engraftment, graft failure or other complications did not differ between ABO compatible or incompatible patients. ABO incompatibility did not show a significant impact on graft-versus-host disease, overall survival or disease-free survival. Factors associated with the need for prolonged red blood cell support were ABO incompatibility (p=0.0395), HLA disparity between donor and recipient (p=0.004) and the onset of hemorrhagic cystitis (p=0.015). In multivariate analysis HLA disparity was the only statistically significant condition (p=0.004). DISCUSSION: ABO incompatibility does not represent a barrier to allogeneic HSCT. It is, however, associated with prolonged transfusion requirements. Close immunohematological monitoring, as a shared standard procedure, allows appropriate transfusion support to be provided and limits post-HSCT immuno-hematological complications.

ABO antibody titres: a multisite comparative study of equivalency and reproducibility for automated solid-phase and haemagglutination titration, and manual dilution with gel column agglutination technology.

BACKGROUND: ABO antibody titres are important in many clinical decisions; however, much variability is observed in titre results. For reliable and reproducible titre results, automated ABO titration methods have been developed. In this 10-site study, we evaluated the equivalency of the automated ABO titration assays on the Galileo NEO, a fully automated blood bank analyzer (Immucor, Inc.) to manual titration with gel Column Agglutination Technology (CAT), as well as the reproducibility of both methods. MATERIALS AND METHODS: Ten different locations participated in this study. The equivalency study included 70 random samples at each site. The reproducibility study tested the same blinded 30-sample panel at each study site. Anti-A and anti-B IgM and IgG antibody titres were tested with both the automated and manual methods; additionally, dithiothreitol (DTT) treatment was used to inactivate IgM antibodies in the manual CAT method. RESULTS: The equivalency between CAT manual method and Galileo NEO automated titres at each site ranged from 38 to 88%; equivalency for each isotype was 66.2% for IgM, 60.6% for IgG, and 88.5% for DTT-treated IgG. The reproducibility study evaluated the titre variation of each sample obtained from the 10 sites. The average titre ranges (in doubling dilutions) for the automated and manual methods, respectively, were 2.15±1.0 and 4.03±1.8 for IgM, and 1.53±0.7 and 4.10±1.9 for IgG; for the manual DTT-treated IgG, the average titre range was 3.45±1.8 doubling dilutions. DISCUSSION: The results demonstrated that the Galileo NEO automated and manual CAT ABO titres are not equivalent. However, the study also demonstrated that titre reproducibility is enhanced with the Galileo NEO automated ABO titration assays relative to the manual CAT ABO titration method. Therefore, to improve management of patients receiving care across multiple institutions, our study supports the use of automated ABO titration.

Clinical effectiveness of platelets in additive solution treated with two commercial pathogen-reduction technologies.

BACKGROUND: Two noninferiority, randomized, controlled trials were conducted in parallel comparing the safety and efficacy of platelets treated with Intercept or Mirasol pathogen-reduction technologies versus standard platelets. STUDY DESIGN AND METHODS: The primary endpoint was the percentage of hematology patients who developed World Health Organization Grade 2 or greater bleeding. A noninferiority margin of 11% was chosen based on expected Grade 2 or greater bleeding in 20% of controls. The study was closed for financial restrictions before reaching the planned sample size of 828 patients, and an intention-to-treat analysis was conducted on 424 evaluable patients. RESULTS: In the Intercept trial (113 treated vs. 115 control patients), the absolute risk difference in Grade 2 or greater bleeding was 6.1%, with an upper one-sided 97.5% confidence limit of 19.2%. The absolute risk difference in the Mirasol trial (99 treated vs. 97 control patients) was 4.1%, and the upper one-sided 97.5% confidence limit was 18.4%. Neither absolute risk difference was statistically significant. In both trials, posttransfusion platelet count increments were significantly lower in treated versus control patients. Mean blood component use in treated patients versus controls was 54% higher (95% confidence interval, 36%-74%; Intercept) and 34% higher (95% confidence interval, 16%-54%; Mirasol) for platelets and 23% higher (95% confidence interval, 8%-39%; Intercept) and 32% higher (95% confidence interval, 10%-57%; Mirasol) for red blood cells. Unexpected reactions and adverse events were not reported. Mortality did not differ significantly between treated and control patients. CONCLUSION: Although conclusions on noninferiority could not be drawn due to low statistical power, the study provides additional information on the safety and efficacy of pathogen-reduced platelets treated with two commercial pathogen-reduction technologies.

Hemolysis in patients with antibody deficiencies on immunoglobulin replacement treatment.

BACKGROUND: Immunoglobulin (Ig)G replacement with intravenous or subcutaneous immunoglobulins is a lifelong substitutive therapy in patients with primary antibody deficiencies (PADs). Hemolysis after immunoglobulin therapy was described in patients receiving high immunoglobulin dosages. The issue of hemolysis after immunoglobulin administration at replacement doses has been considered of little clinical significance. STUDY DESIGN AND METHODS: This was a single-center observational study over a 2-year period on immunoglobulin-induced hemolysis in a cohort of 162 patients with PADs treated with immunoglobulin administered at replacement dosages. RESULTS: Six patients had signs and symptoms of immunoglobulin-induced hemolysis. Two additional asymptomatic patients were identified by a short-term study run on 16 randomly selected asymptomatic patients. Alloantibodies eluted from patients' red blood cells (RBCs) had anti-A and Rh specificities (anti-D and anti-C). The immunoglobulins contained alloantibodies with the same specificities of the antibodies eluted from patients' RBCs. CONCLUSION: Hemolysis occurred in patients receiving immunoglobulin at replacement dosages. Polyvalent immunoglobulin preparations contained multiple clinically significant antibodies that could have unexpected hemolytic consequences, as anti-C whose research and titration are not required by the European Pharmacopoeia. The issue of hemolysis in long-term recipients of immunoglobulin treatment administered at replacement dosages should be more widely recognized.